The chemical diversity of natural antioxidants (AOXs) makes it difficult to
separate, detect, and quantify individual antioxidants from a complex
food/biological matrix. Moreover, the total ...antioxidant power is often more
meaningful to evaluate health beneficial effects because of the cooperative
action of individual antioxidant species. Currently, there is no single
antioxidant assay for food labeling because of the lack of standard
quantification methods. Antioxidant assays may be broadly classified as the
electron transfer (ET)- and hydrogen atom transfer (HAT)-based assays. The
results obtained are hardly comparable because of the different mechanisms,
redox potentials, pH and solvent dependencies, etc. of various assays. This
project will aid the identification and quantification of properties and mutual
effects of antioxidants, bring a more rational basis to the classification of
antioxidant assays with their constraints and challenges, and make the results
more comparable and understandable. In this regard, the task group members
convey their own experiences in various methods of antioxidants measurement.
Comparative estimations of the antioxidant activity of methanolic extracts from biomasses of different types of in vitro cultures of
, and
and also from plant raw materials were performed. The ...antioxidant measurements were based on the modern assays-cupric ion reducing antioxidant capacity (CUPRAC) and quick, easy, new, cheap, and reproducible CUPRAC (QUENCHER-CUPRAC). The total extractable antioxidants (CUPRAC assay) ranged from 10.4 to 49.7 mmol (100 g)
of dry weight (DW) expressed as Trolox equivalent antioxidant capacity (TEAC), and the global antioxidant response (QUENCHER-CUPRAC assay) ranged from 16.0 to 79.1 mmol (100 g)
DW for in vitro cultures, whereas for plant raw materials the total extractable antioxidants ranged from 20.9 to 69.5 mmol (100 g)
DW, and the global antioxidant response ranged from 67.2 to 97.8 mmol (100 g)
DW. Finally, the in vitro cultures could be regarded as an antioxidant-rich alternative resource for the pharmaceutical, health food and cosmetics industries.
It was aimed in this study to identify and quantify various constituents (particularly phenolics) of apple juice and to quantitatively compare the total antioxidant capacities of juices obtained from ...apple varieties grown in Turkey.
Experimental studies were performed by determining the total antioxidant capacities using two spectrophotometric methods, cupric ion reducing antioxidant capacity (CUPRAC) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate) (ABTS) methods, and by identification and quantification of the leading antioxidant constituents individually with HPLC. The total antioxidant capacity (TAC) values of HPLC-quantified antioxidant constituents were found, and compared with those found by CUPRAC and ABTS. The TAC of HPLC-quantified compounds accounted for between 40.0% and 70.6% of the observed CUPRAC capacities of apple juices with respect to apple varieties.
The order of antioxidant capacity of apple juices determined by the CUPRAC and ABTS methods were: Ervin Spur
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King Luscious
>
Sky Spur
>
Amasya
>
Arap Kizi
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Granny Smith
>
Lutz Golden.
A validated silver nanoparticle assay (SNaP-C) for quantitation of Vitamin C, as ascorbic acid (AA) and total AA (TAA), was applied to 31 beverages. SNaP-C assay results (LOD of 2.2 mg/L AA) were ...compared to AA and TAA determined by high-performance liquid chromatography with UV/Vis (LOD = 0.4 mg/L AA), and two well-known assays. All approaches were calibrated using meta-phosphoric acid stabilized AA, where the reducing agent tris(2-carboxyethyl) phosphine hydrochloride was added to convert dehydroascorbic acid to AA for determination of TAA. Statistical comparisons of these four resulting datasets were completed. SNaP-C and HPLC were not statistically significantly different (P > 0.05) for comparison of AA and TAA (mg/L) in these samples, whereas the CUPRAC and Folin-Ciocalteu assays statistically significantly overestimated values of AA and TAA content, respectively. The SNaP-C method is a novel assay that has high specificity for AA capable of quantifying TAA with addition of TCEP.
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•Ascorbic acid is selectively quantified using silver nanoparticles (SNaP-C).•SNaP-C assay results were compared to HPLC, CUPRAC, and Folin-Ciocalteu.•SNaP-C assay results were statistically comparable to HPLC results.•Low LOD and LOQ were observed using SNaP-C for AA and DHAA.
This study aimed to determine the effect of different drying methods namely, hot air drying (HAD), freeze-drying (FD), vacuum drying (VD), and ultrasound-assisted vacuum drying (USVD) on drying ...kinetic, total bioactive compounds, lycopene and β-carotene, phenolic composition and color quality of rosehip. Drying times of the rosehips for USVD, VD, and HAD were 180, 300, and 1140 min, respectively, indicating that USVD significantly reduced drying time of rosehip. The results of total bioactive compounds, lycopene and β-carotene, phenolic composition showed that FD resulted the highest bioactive compounds, followed by VD, USVD, and HAD. DPPH and CUPRAC results showed that FD dried samples showed highest antioxidant activity than fresh and all dried samples while HAD showed lowest antioxidant activity. USVD and FD exhibited a lower ΔE value than HAD and VD, indicating that they had similar color properties to the fresh sample. USVD resulted in lower drying time and color change than VD and HAD, while USVD showed lower bioactive compounds retention than VD. This study suggested that USVD could be used as an alternative to HAD due to its lower drying time and higher bioactive compound and color retention than HAD.
•UAVD significantly reduced drying time compared to VD and HAD.•FD resulted the highest bioactive compounds followed by VD, UAVD, and HAD.•UAVD and FD exhibited a lower ΔE value than HAD and VD.•UAVD could be used alternative drying method to HAD in a drying of rosehip.
This study aims to investigate the effects of different drying methods namely, ultrasound-assisted vacuum-drying (USV), freeze-drying (FD), infrared-drying (ID) and hot-air drying (HAD) on bioactive ...compounds, phenolic profile, in vitro bioaccessibility of phenolic compounds, color change, sugar profile and HMF formation of persimmon fruits. Total phenolic contents (TPC) were 77.2, 112.5, 124.9 and 262.4 mg GAE/100 g for HAD, ID, USV, and FD, respectively. CUPRAC, DPPH, β-carotene and lycopene level were 219.2–635.2 mg TE/100 g, 101.1–299.7 mg TE/100 g, 294.3–438.5 mg/100 g and 720.6–966.5 mg/100 g, respectively. Drying methods significantly affected both amounts of individual phenolics and their distribution (P < 0.05). Epigallocatechin was determined as a major phenolic compound for all samples (88.2–383.2 mg/100 g). All drying process significantly increased the bioaccessibility of phenolic compounds (P < 0.05). HAD showed the highest in vitro bioaccessibility. All drying methods significantly affected ΔE values (P < 0.05). HMF values were 12.1, 15.0 and 23.4 mg/kg for ID, USV and HAD samples, respectively and was not found for FD. This study suggested that USV and ID could be used as an alternative drying method to FD and conventional drying due to high drying rate, less phenolic degradation, HMF formation, and color change.
•ID and USV exhibited higher drying rate compared to conventional drying.•FD, USV, and ID showed higher antioxidant capacity than conventional drying.•Drying methods significantly affected the distribution of phenolics.•HAD and ID showed the highest bioaccessibility.•ID and USV could be used as an alternative drying method.
In this study, the SNPAC method was developed by using hypochlorous (ClO−) at pH 9.3. Polyvinylpyrrolidone (PVP) was used as a stabilizer. The existence of HOCl enables to formation stronger and more ...stable yellow emission which gives sensitivity. As a result, lower LOD and LOQ values were achieved by the AgNP–HOCl method. The obtaining lower values was attributed to the reoxidation of silver atoms with ClO− ions in the presence of PVP. The newly modified method was applied to the total antioxidant capacity (TAC) measurement of Boswellia Serrata, Aronia Melanocarpa tea, and juice. The results were compared with the results obtained by application of CUPRAC (Cupric ion Reducing Antioxidant Capacity) and FRAP (Ferric Reducing Antioxidant Power) assays. The TAC values of Boswellia Serrata, Aronia Melanocarpa tea, and juice were found as 6.18, 137.98, and 12.08 mmol TEAC/kg, respectively.
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•The study optimized the AgNP–HOCl assay with varying HOCl concentrations and time intervals.•PH adjustment experiments showed maximum absorbance for samples with pH 9.3.•Citrate reduction method combined with PVP was effective in synthesizing well-dispersed AgNP–HOCl.•Lower LOD and LOQ values were achieved by AgNP–HOCl method.•Cost-effective and easily applicable assay would be practiced in analysis of food matrices.
Oxidative stress is damage caused by reactive oxygen species Compounds that can prevent oxidative stress are antioxidants. The brotowali plant (Tinospora crispa) has been used for the treatment of ...diabetes and hypertension. The brotowali plant contains secondary metabolites such as flavonoids. Flavonoids are known to be a class of compounds that have antioxidant activity. so it can be kind of solvent which is the most excellent in the test plant extract brotowali. Extraction was conducted by reflux-rise that use nhexane, ethyl acetate and ethanol 96%. Determination of antioxidant activity using them CUPRAC method. Determination of total flavonoid content using colorimetric aluminum chloride method with quercetin as standard. The results showed that the ethyl acetate extract sample had strong antioxidant activity compared to the extract sample with 96% ethanol and n-hexane. The EC50 value of the ethyl acetate extract was 53.637 g/mL. Extract with n-hexane solvent had the highest flavonoid content, namely 9,937 ± 0.009 gQE/100 g extract.
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•The antioxidant potential of different humic substances (HS) fractions obtained from Leonardite was determined.•IHSS standards and our HS fractions (humic (HA), fulvic (FA) and ...hymatomelanic (HY) acids) were investigated.•The TPC with Folin-Ciocalteu method, the CUPRAC and QUENCHER-CUPRAC assays and ESR method were used.•The HA fractions contain the most phenolic moieties followed by the HY and then FA samples.•The antioxidant effect of the HS fractions correlates well with the active ingredients of some plant extracts.
An increasing proportion of the population in the Western world suffers from one of the oxidative stress related diseases. Although the radical-scavenging and therapeutic potential of humic substances (HSs) are known, little is known about their antioxidant properties and structure-property relationships. The aim of the research is to reveal the antioxidant potential of different HS samples and to compare them with already well-known antioxidants like gallic acid and Trolox. We determined the total phenolic content (TPC) of the samples using Folin-Ciocalteu (FC) method because it is generally associated with the antioxidant effect. We also applied the CUPRAC (CUPric Reducing Antioxidant Capacity) and QUENCHER-CUPRAC methods to achieve a comprehensive picture about the antioxidant potential of HSs. Furthermore, we tested the HS samples using electron spin resonance (ESR) method as a new tool to characterize the antioxidant properties. According to the results of FC method given in gallic acid equivalent antioxidant capacity (GAEAC) the HA fractions contain the most phenolic moieties (300–470 mg GAE/g) which is followed by the HY (150–175 mg GAE/g) and then FA (80–155 mg GAE/g). The antioxidant capacities of HS samples were related to Trolox (Trolox equivalent antioxidant capacity (TEAC)) in addition to gallic acid (GAEAC), namely 5–35 µmol GAE/g, 50–310 µmol TE/g and 12–42 µmol GAE, 175–530 µmol TE /g obtained by CUPRAC and QUENCHER-CUPRAC methods, respectively. The ESR results supported that the tested HS samples have antioxidant properties. Moreover, we compared the results of our fractions with the standard samples of the IHSS, in terms of origin and extraction methods. We could conclude that, in addition to the source of raw materials for the fractions, the method of their extraction also greatly influences their antioxidant effect.
Stres oksidatif adalah kerusakan yang diakibatkan oleh spesi oksigen reaktif. Senyawa yang dapat mencegah terjadinya stres oksidatif yaitu antioksidan. Tanaman brotowali (Tinospora crispa) telah ...digunakan untuk pengobatan diabetes dan hipertensi. Tanaman brotowali mengandung senyawa metabolit sekunder diantaranya yaitu flavonoid. Flavonoid diketahui merupakan golongan senyawa yang merniliki aktivitas antioksidan. Penelitian bertujuan untuk mengetahui aktivitas antioksidan pada batang brotowali yang diekstraksi dengan pelarut berbeda kepolaran, sehingga dapat diketahui jenis pelarut manakah yang paling baik dalam mengekstrak tanaman uji batang brotowali. Ekstraksi dilakukan dengan metode refluks bertingkat menggunakan pelarut n-heksana, etil asetat dan etanol 96%. Penetapan aktivitas antioksidan menggunakan metode CUPRAC. Penetapan kadar flavonoid total menggunakan metode aluminium klorida kolorimetri dengan kuersetin sebagai standar. Hasil menunjukan sampel ekstrak etil asetat memiliki aktivitas antioksidan yang kuat dibandingkan sampel ekstrak dengan etanol 96% dan n-heksana. Nilai ECso ekstrak etil asetat sebesar 53,637 µg/mL. Ekstrak dengan pelarut n-heksana merniliki kadar flavonoid paling tinggi yaitu 9,937 ± 0,009 gQE/100 g Ekstrak.
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